JPH02292302A - Prevention of deposition of polymer scale - Google Patents

Abstract

PURPOSE:To prevent polymer scale from depositing on the inside wall, etc., of a polymerizer by polymerizing an ethylenically unsaturated monomer in a polymerizer having an inside wall coated with a film containing an ester derivative of a tannin. CONSTITUTION:An ethylenically unsaturated monomer is polymerized in a polymerizer having an inside wall coated with a film containing an ester derivative of a tannin. The ester derivative is one obtained by adding an acid halide to a tannin in an aqueous alkaline solution and heating the mixture. Examples of the tannin used desirably include tannic acid, Turkish gallotannin and kaki- shibu tannin. According to the above process, the polymerizer can be used repeatedly without deposition of polymer scale by performing the coating once for each or several batches.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing the adhesion of polymer scale to the inner wall surface of a polymerization vessel during the polymerization of monomers having ethylenic double bonds.

[Conventional technology]

BACKGROUND ART In a method of producing a polymer by polymerizing monomers in a polymerization vessel, there is a known problem that the polymer adheres as scale to the inner wall surface of the polymerization vessel. If polymer scale adheres to the inner wall surface of the polymerization vessel, the polymer yield and cooling capacity of the polymerization vessel may decrease, and the adhered polymer scale may peel off and be mixed into the product, resulting in a decrease in the quality of the product polymer. Furthermore, there are disadvantages such as a great deal of effort and time being required to remove the polymer scale.

Conventionally, as a method for preventing polymer scale from adhering to the inner wall surface of a polymerization vessel, for example, a method of applying polar compounds, dyes, pigments, etc. to the inner wall surface (Japanese Patent Publication Nos. 45-30343 and 45-30835) has been used. , a method of applying an aromatic amine compound (Japanese Unexamined Patent Publication No. 51-50887), a method of applying a reaction product of a phenolic compound and an aromatic aldehyde (Japanese Unexamined Patent Publication No. 55-54317), etc. have been proposed. .

These methods are effective in preventing polymer adhesion in the polymerization of vinyl halide monomers such as vinyl chloride, or monomer mixtures mainly consisting of vinyl chloride and containing a small amount of monomers that can be copolymerized with this monomer. It is.

[Problem to be solved by the invention]

However, in the conventional method described above, the scale prevention effect depends on various polymerization conditions such as the type of monomer used, the mixing ratio of each component used, the type of polymerization catalyst, the polymerization type, and the material of the inner wall of the polymerization vessel. However, it has been difficult to effectively and reliably prevent polymer scale from adhering to the inner wall surface of the polymerization vessel and to the stirring blades, stirring shafts, baffles, etc. with which monomers come into contact during polymerization.

Therefore, the purpose of the present invention is to effectively prevent scale adhesion regardless of the type of monomer used, the mixing ratio of the components used, the type of polymerization catalyst, the material of the inner wall of the polymerization vessel, etc. Another object of the present invention is to provide a method in which the resulting polymer product is not colored.

[Means to solve the problem]

The present invention solves the above-mentioned problems by providing a method for preventing the adhesion of polymer scale during the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, and preferably on the inner wall surface of the polymerization vessel. , Preventing the adhesion of polymer scale by carrying out the polymerization in a polymerization vessel in which a coating film containing an ester derivative of tannins is previously formed on other parts that the monomer comes into contact with during polymerization. The present invention provides a method.

The ester derivatives of tannins used as the main component of the coating solution are obtained by adding acid halides to tannins in an alkaline aqueous solution and reacting them by heating.

Here, the tannins include, for example, tannin L fivefold tannin, tannin tannin, sumac tannin, cod tannin, valonia tannin, chestnut tannin,
Hydrolyzable tannins such as myrobalantannin, oak tannin, dividivitannin, algarobia tannin: gambian tannin, kephracho tannin, mimosa tannin, mangrove tannin, hemlot ivy tannin, subruce tannin, Burma tannin, oak bark tannin , reduced type tannins such as persimmon tannins, and the like. These may be used alone or in combination of two or more. Among these, tannic acid, five-fold tannin, gallic tannin, kefracho tannin, mimosa tannin, oak bark tannin, and persimmon astringent tannin are preferred.

Examples of acid halides used in the production of ester derivatives of tannins include formyl chloride, acetyl chloride, isobutyryl chloride, benzoyl chloride, and the like. These may be used alone or in combination of two or more.

In the production of ester derivatives of tannins, the ratio of tannin/acid halide used is usually 9 by weight.
It is preferably 5/5 to 10/90, and more preferably 90/10 to 30/70. If the amount of tannins used is too large or too small, the yield of the resulting derivative may decrease.

Examples of the alkaline solution used include aqueous solutions of alkaline substances such as sodium hydroxide and potassium hydroxide. The concentration of the alkaline substance is usually preferably 1 to 50% by weight, more preferably 5 to 30% by weight.

The reaction is usually carried out at 10 to 200°C, preferably 20 to 10
The reaction is carried out at a temperature of 0° C., usually for about 0.1 to 24 hours, preferably about 0.5 to 10 hours, with stirring.

The coating film formed by the method of the present invention is formed by applying a coating liquid prepared by dissolving or decomposing the tannin ester derivative obtained as described above in an appropriate solvent to a predetermined location. Ru.

The concentration of the ester derivative of tannins in the coating solution is not particularly limited as long as the amount of coating described below can be obtained, but usually,
0.005-5% by weight, preferably 0.05-2% by weight
That's about it.

Examples of the solvent used in preparing the coating solution include water;
methanol, ethanol, probanol, buknol,
Alcohol solvents such as 2-butanol, 2-methyl-1-probanol, 2-methyl-2-probanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 2-pentanol; acetone, methyl ethyl ketone, methyl isobutyl Ketone solvents such as ketones; methyl formate,
Ester solvents such as ethyl formate, methyl acetate, and methyl acetoacetate; 4-methyldioxolane, ethylene glycol diethyl ether, 1.4-'; ether solvents such as oxane; furans such as tetrahydrofuran; dimethylformamide, dimethyl Aprotic solvents such as sulfoxide and acetonitrile; aliphatic hydrocarbon solvents such as n-hexane and n-pentane; aromatic hydrocarbon solvents such as toluene and xylene. 1,1.1-}lichloroethylene,
1, l, 1. Examples include halogenated hydrocarbon solvents such as 2-tetrachlorethylene, which may be used alone or as a mixed solvent of two or more.

In the method of the present invention, in order to form a coating film that prevents polymer scale from adhering to the inner wall surface of the polymerization vessel, a coating solution containing the ester derivative of tannins is applied to the inner wall surface of the polymerization vessel, and preferably to the polymerization vessel inner wall surface. other parts in contact with the monomers,
For example, it may be applied to a stirring shaft, stirring blades, etc., and then sufficiently dried at a temperature of room temperature to about 100°C. Also,
The inner wall of the polymerization vessel and the parts that will come into contact with other monomers are preliminarily coated (
The coating solution may be applied after heating (to about 30 to 80°C). In either case, a coat can be obtained by washing the coated surface with water if necessary after it has sufficiently dried.

In the coating film obtained as described above, the coating amount of the ester derivative of tannins is usually o. oos~5g/m
It is preferably 2 or more, particularly 0.05 to 2 g/i. In the present invention, the above coating operation may be performed every batch of polymerization, but it is not necessary to perform it every batch because the formed coating film has considerable durability and the scale prevention effect lasts. Usually, it is sufficient to perform the process 1 to 10 times per batch.

After the coating process has been completed on the inner wall of the polymerization vessel and other parts that come into contact with the monomer during polymerization, the monomer having an ethylenic double bond and the polymerization initiator are added to the polymerization vessel in a conventional manner. , and other necessary polymerization media and additives, such as monomer dispersion aids, may be added and polymerized.

Examples of monomers having an ethylenic double bond to which the method of the present invention is applied include vinyl halides such as vinyl chloride, vinyl esters such as vinyl acetate and vinyl propionate, acrylic acid, methacrylic acid, and their like. Examples include esters or salts, maleic acid or fumaric acid, and their esters or anhydrides, diene monomers such as butadiene, chloroprene, and isoprene, as well as styrene, acrylonitrile, vinylidene halides, and vinyl ethers.

Further, the method of polymerization to which the method of the present invention is applied is not particularly limited, and any polymerization method such as suspension polymerization, emulsion polymerization, bulk polymerization, and gas phase polymerization is effective.

Therefore, any commonly used additives added to the polymerization system can be used without any restrictions. That is,
For example, t-butyl peroxyneodecanate, di-2
-Ethylhexyl oxydicarbonate, 3,5.
5-} Limethylhexanoel peroxide, α-cumyl peroxyneodecanoate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl peroxypiparate, di-2-ethoxyethyl peroxydicarbonate, penzoyl peroxide , lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, α,α′-azobisisobutyronitrile, α,α
Polymerization catalysts such as 2.4-dimethylbaret nitrile, potassium persulfate, ammonium persulfate, and p-menthane hydroperoxide; Suspending agents such as polymers, cellulose derivatives such as hydroxypropyl methylcellulose, natural or synthetic polymer compounds such as gelatin; Solid tit agents such as calcium phosphate and hydroxyapatite; Sorbitan monolaurate, sorbitan triolate, polyoxy Nonionic emulsifiers such as ethylene alkyl ether; anionic emulsifiers such as sodium alkylbenzenesulfonates such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate, and sodium dioctyl sulfosuccinate; fillers such as calcium carbonate and titanium oxide; tribasic lead sulfate , stabilizers such as calcium stearate, diptyltin dilaurate, and dioctyltin mercabutide; lubricants such as rice wax, stearic acid, and cetyl alcohol; D
O Plasticizers such as PDBP; chain transfer agents such as trichlorethylene and mercabutanes. Even in a polymerization system in which a p}+ regulator is present, the method of the present invention can effectively prevent the adhesion of polymer sgale.

[Example] Next, the method of the present invention will be explained using Examples and Comparative Examples. In addition, in each table below, the mark * is {(J experiment N
o is a comparative example, and other experiment No. is an example of the present invention.

゛′L(1) derivative N
Preparation of α1 After dissolving 30 g of tannic acid in 300 g of water, 30 g of benzoyl chloride was added. Next, 25 g of a 20% aqueous potassium hydroxide solution was added, and the mixture was reacted with stirring at 30° C. for 1 hour.

The resulting reaction mixture was filtered, washed 5 to 6 times with water, and then dried to obtain 145 g of derivative Nα.

(2) Derivative No. After dissolving 40 g of oyster tannin produced in step 2 in 300 g of water,
10 g of acetyl chloride was added. Next, 20 g of a 20% aqueous potassium hydroxide solution was added, and the mixture was reacted with stirring at 30°C for 1 hour.

The resulting reaction mixture was filtered, washed 5 to 6 times with water, and then dried to obtain 247 g of derivative Nα.

(3) Production of derivative Nα3 After dissolving 30 g of gallic tannin in 300 g of water, 20 g of benzoyl chloride was added. Next, 20 g of a 20% aqueous sodium hydroxide solution was added, and the mixture was reacted with stirring at 50° C. for 0.5 hour.

The resulting reaction mixture was filtered, washed 5-6 times with water, and then dried to give derivative no. 340 g was obtained.

Example 1 Polymerization was carried out in the following manner using a stainless steel polymerization vessel with an internal volume of too g and equipped with a stirrer.

In each experiment, first, as shown in Table 1, a coating solution was prepared by dissolving the ester derivatives of tannins produced as above in a solvent, and this was applied to the inner wall of the polymerization vessel and other areas where monomers were coated during polymerization. It was applied to the contact area, heated at 50°C for 15 minutes, dried, and then washed with water. However, experiment hi~3
does not apply a coating liquid or contains only tannins. This is a comparative example in which a coating liquid was applied. Table 1 shows the ester derivatives of tannins used in each experiment, their concentrations, and the solvents used.

Thereafter, 400 kg of water, 200 kg of vinyl chloride, 250 g of partially saponified polyvinyl alcohol, 25 g of hydroxypropylene methylcellulose, and 75 g of diisopropyl peroxydicarbonate were added to the polymerization vessel in which the coating film had been formed. Preparation and stirring 7
Polymerization was carried out at 5°C for 6 hours. After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 1.

Table 1 Example 2 The same coating liquid as that used in the experiment Nα shown in Table 2 was added to a stainless steel polymerization vessel with an internal volume of 201 mm in Example 1 and was equipped with a stirrer.
A coating film was formed by coating in the same manner as above.

However, experiment Nα13 is a comparative example in which no coating liquid is applied.

Next, 9 kg of water was added to the polymerization vessel coated in this way.
, 225 g of sodium dodecylbenzenesulfonate,
After charging 12 g of t-dodecylbutane and 13 g of potassium persulfate and purging with nitrogen gas, 1.5 g of styrene was added.
Charge 3 kg and 3.8 kg of butadiene and heat at 50°C for 2 hours.
Polymerization was carried out for 0 hours.

After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 2.

Table 2 [Effects of the Invention] According to the method of the present invention, polymerization can be effectively performed regardless of the type of monomer used, the mixing ratio of the components used, the type of polymerization catalyst, the material of the inner wall of the polymerization vessel, etc. Adhesion of coalescing scale can be prevented. For example, it is possible to effectively prevent polymer scale from adhering to the inner wall surface of a polymerization vessel during the polymerization of monomers having ethylenic double bonds, which has been difficult in the past. In the method of the present invention, by applying the coating liquid in every batch or once every few batches, the polymerization vessel can be used repeatedly without depositing polymer scale.

Claims (1)

[Claims] A method for preventing the adhesion of polymer scale during the polymerization of monomers having ethylenic double bonds in a polymerization vessel, the method comprising forming a coating film containing an ester derivative of tannins on the inner wall surface of the polymerization vessel in advance. A method for preventing the adhesion of polymer scale, which comprises carrying out the polymerization in a polymerization vessel comprising: